No 100 HZ timer !
Quoted 3 lines
Quoted 3 lines
Just how would you do kernel/user CPU time accounting then ? It's
currently done
Quoted 3 lines
Quoted 1 line
on every timer tick, and doing it less often would make it useless.
On the contrary doing it less often but at the right time massively
improves
Quoted 1 line
its accuracy. You do it on reschedule. An rdtsc instruction is cheap and
all
Quoted 1 line
of a sudden you have nearly cycle accurate accounting
If you do the accounting on reschedule, how do you find out how much time has been spent in user versus kernel mode? Or do the Intel chips have two counters, one for user space execution and one for the kernel?
blue skies,
Martin
Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: [email protected]
Quoted 5 lines
If you do the accounting on reschedule, how do you find out how much ti= me
has been spent in user versus kernel mode? Or do the Intel chips have t= wo
counters, one for user space execution and one for the kernel?
Unfortunately not so you'd need to do a little bit per syscall, at least for non trivial syscalls.